Process and apparatus for distributing hydrocarbon feed and catalyst

ABSTRACT

A process and apparatus for fluid catalytic cracking feeds catalyst to a chamber of a riser. The catalyst exits the chamber and passes through a plenum and into a reaction zone through a plurality of tubes which distribute the catalyst uniformly over a cross section of the reaction zone of the riser. A hydrocarbon feed is fed to the plenum. The hydrocarbon feed passes from the plenum into the reaction zone through a plate comprising a multiplicity of openings which distribute the hydrocarbon feed uniformly over a cross section of the reaction zone of the riser. The feed is contacted with the catalyst in a reaction zone of the riser.

BACKGROUND OF THE INVENTION

The invention relates to a process and apparatus for feeding hydrocarbonfeed to be contacted with catalyst. A field of the invention may be thefield of fluid catalytic cracking (FCC).

FCC is a hydrocarbon conversion process accomplished by contactinghydrocarbons in a fluidized reaction zone with a catalyst composed offinely divided particulate material. The reaction in catalytic cracking,as opposed to hydrocracking, is carried out in the absence ofsubstantial added hydrogen or the consumption of hydrogen. As thecracking reaction proceeds substantial amounts of highly carbonaceousmaterial referred to as coke are deposited on the catalyst to providecoked or carbonized catalyst. This carbonized catalyst is often referredto as spent catalyst. However, this term may be misconstrued because thecarbonized catalyst still has significant catalytic activity. Vaporousproducts are separated from carbonized catalyst in a reactor vessel.Carbonized catalyst may be subjected to stripping over an inert gas suchas steam to strip entrained hydrocarbonaceous gases from the carbonizedcatalyst. A high temperature regeneration with oxygen within aregeneration zone operation burns coke from the carbonized catalystwhich may have been stripped.

FCC can create a variety of products from heavier hydrocarbons. Often, afeed of heavier hydrocarbons, such as vacuum gas oil, is provided to anFCC reactor. Various products may be produced, including a gasolineproduct and/or light olefins, such as at least one of propylene andethylene. To produce more light olefins, product cuts from FCC effluent,such as naphtha, may be recycled to the riser reactor or to anadditional riser reactor for additional catalytic cracking These productcuts may be fed to the riser in a gaseous phase. Feed distributed to theriser in liquid phase is typically vaporized upon injection into theriser.

A problem encountered during the FCC process is distributing the feed inthe riser so that it can adequately mix with the catalyst. Adequatemixing is usually necessary for efficient conversion of the feed.Hydrocarbon feed distributors spray dispersion steam and hydrocarbonfeed into the riser typically transversely to a flowing stream ofcatalyst that is propelled upwardly by a fluidizing, lift gas. Arelationship between injected feed velocity, drop size and momentumlimits the horizontal travel of the injected hydrocarbon feed againstthe lift gas and catalyst accelerating vertically, upwardly in theriser. Additionally, a dense core of catalyst may develop in the axialcenter of the riser that resists penetration by the vaporous hydrocarbonfeed. Larger riser diameters may exacerbate this problem because of theinherent difficulty in distributing the feedstock further toward thecenter of the riser.

Recycled feeds such as lighter hydrocarbon feeds derived from fluidcatalytic cracked products may be recycled or fed to a reactor riser invaporous phase. Penetration of vaporous feed into a flowing stream ofcatalyst is also difficult because of the lower density of the vaporousfeed.

It may be desirable to provide a distributor for distributinghydrocarbon feed and catalyst to an FCC reactor from the same location.

SUMMARY OF THE INVENTION

This invention relates generally to an improved FCC process andapparatus. Specifically, this invention may relate to an improved feedand catalyst distributor and may be useful for FCC operation todistribute feed and catalyst into a reactor riser.

In a process embodiment, the present invention is a process for fluidcatalytic cracking comprising passing catalyst to a reaction zone of ariser through a plate. Hydrocarbon feed is fed to the reaction zone of ariser through the plate. Lastly, the feed is contacted with the catalystin the reaction zone of the riser.

In an additional process embodiment, the present invention is processfor fluid catalytic cracking comprising passing hydrocarbon feedupwardly in a riser from a multiplicity of first openings spread outuniformly over a cross section of the riser. Catalyst is passed upwardlyin the riser from a plurality of second openings spread out uniformlyover a cross section of the riser. Lastly, the catalyst and thehydrocarbon feed are contacted in the riser.

In a further process embodiment, the present invention is process forfluid catalytic cracking comprising feeding catalyst to a chamber of ariser. The catalyst exits the chamber and passes through a plenum andinto a reaction zone through a plurality of tubes which distribute thecatalyst uniformly over a cross section of the reaction zone of theriser. Hydrocarbon feed is fed to the plenum. The hydrocarbon feed ispassed from the plenum into the reaction zone through a plate comprisinga multiplicity of openings which distribute the hydrocarbon feeduniformly over a cross section of the reaction zone of the riser.Lastly, the feed is contacted with the catalyst in a reaction zone ofthe riser.

In an apparatus embodiment, the present invention is apparatus for fluidcatalytic cracking comprising a riser and a reaction zone in the riser.A plate defines the reaction zone with a first opening in the plate forpassing hydrocarbon feed to the reaction zone and a second opening inthe plate for passing catalyst to the reaction zone.

In an additional apparatus embodiment, the present invention is anapparatus for fluid catalytic cracking comprising a riser and a chamberincluding an upper barrier. A plurality of openings is in communicationwith the chamber. The openings are spaced uniformly over the crosssection of the riser. A plenum including a plate with a multiplicity ofopenings spread out uniformly over a cross section of the riser. Lastly,a reaction zone in the riser is in communication with the chamber andthe plenum through the plurality of openings and the multiplicity ofopenings.

In a further apparatus embodiment, the present invention is an apparatusfor fluid catalytic cracking comprising a riser and a reaction zone inthe riser. The apparatus also comprises a fluidizing gas distributor anda catalyst inlet. A chamber is in communication with the catalyst inletand the fluidizing gas distributor. A plenum is in communication with afeed inlet. Lastly, a tube communicates the chamber with the reactionzone and an opening in the plenum communicates the plenum with thereaction zone.

The catalyst and feed distributor evenly distributes the hydrocarbonstream and catalyst over the cross section of the riser from the samelocation to provide better contact as the catalyst and feed flowconcurrently upwardly in the riser.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic, elevational view of an FCC unit incorporating thepresent invention.

FIG. 2 is an enlarged, partial elevational view of a portion of FIG. 1.

FIG. 3 is a further enlarged, partial elevational view of section A ofFIG. 2.

FIG. 4 is a sectional view of FIG. 2 taken at segment 4-4.

DEFINITIONS

The term “communication” means that material flow is operativelypermitted between enumerated components.

The term “downstream communication” means that at least a portion ofmaterial flowing to the subject in downstream communication mayoperatively flow from the object with which it communicates.

The term “upstream communication” means that at least a portion of thematerial flowing from the subject in upstream communication mayoperatively flow to the object with which it communicates.

The term “direct communication” means that flow from the upstreamcomponent enters the downstream component without passing through anintermediate vessel.

The term “feeding” means that the feed passes from a conduit or vesseldirectly to an object without passing through an intermediate vessel.

The term “passing” includes “feeding” and means that the material passesfrom a conduit or vessel to an object.

DETAILED DESCRIPTION OF THE INVENTION

The present invention is an apparatus and process for feeding ahydrocarbon feed and a catalyst stream to a riser to effect contact.Conventionally, hydrocarbon feed is injected from a side of the risertransversely to upwardly flowing catalyst, requiring the catalystmomentum to sweep the feed in an upward direction to contact thecatalyst. The present invention is designed to deliver hydrocarbon feedand catalyst into a reaction zone of the riser from the same location totravel in the same direction, thereby enhancing contact between the two.

In an aspect, the hydrocarbon feed is in vapor phase. The hydrocarbonfeed may be the only hydrocarbon feed fed to the riser or in an additionto another hydrocarbon feed fed to the riser. If an additional feed isfed to the riser, the feed may be a recycled feed derived from risereffluent. Accordingly, the hydrocarbon feed may be a conventional FCCfeed or a light hydrocarbon stream. The feed and catalyst are fed to alower end of a riser in which regenerated catalyst and carbonizedcatalyst may be mixed for contact with the hydrocarbon feed. Theillustrated embodiment, however, only shows feeding regenerated catalystto the riser.

The present invention may be useful in any solids-gas contactingequipment. However, ready usefulness is found in an FCC unit.

FIG. 1 shows an FCC unit 8 having a catalyst and feed distributor 4. TheFCC unit 8 includes a reactor vessel 20 and a regenerator vessel 50. Aregenerated catalyst conduit 12 transfers a regenerated catalyst streamfrom the regenerator vessel 50 at a rate regulated by a control valve 14through a regenerated catalyst inlet 15 of the regenerated catalystconduit 12 to the reactor riser 10. The regenerated catalyst inlet 15 isin communication with the riser 10. An optional carbonized catalystconduit may transfer a second carbonized catalyst stream from thereactor vessel 20 to the reactor riser 10, but this embodiment is notshown.

The riser 10 is an elongated vertical tube typically made of killedcarbon steel. The inner surface of the entire riser 10 may be coatedwith a refractory material. A feed inlet 18 may deliver feed to theriser to be contacted with catalyst. Upon contacting the hydrocarbonfeed with catalyst in the reactor riser 10 the heavier hydrocarbon feedcracks to produce lighter gaseous hydrocarbon product while coke isdeposited on the catalyst particles to produce carbonized catalyst.

A conventional FCC feedstock and higher boiling hydrocarbon feedstockare suitable primary hydrocarbon feeds. The most common of suchconventional feedstocks is a “vacuum gas oil” (VGO), which is typicallya hydrocarbon material having a boiling range of from 343° to 552° C.(650 to 1025° F.) prepared by vacuum fractionation of atmosphericresidue. Such a fraction is generally low in coke precursors and heavymetal contamination which can serve to contaminate catalyst. Heavyhydrocarbon feedstocks to which this invention may be applied includeheavy bottoms from crude oil, heavy bitumen crude oil, shale oil, tarsand extract, deasphalted residue, products from coal liquefaction,atmospheric and vacuum reduced crudes. Heavy feedstocks for thisinvention may also include mixtures of the above hydrocarbons and theforegoing list is not comprehensive.

It is also contemplated that lighter recycle or previously cracked feedssuch as naphtha may be a suitable secondary or the only hydrocarbonfeedstock to the riser. A light naphtha fraction suitable as the onlyfeed or a secondary feed to the riser may have an initial boiling point(IBP) below about 127° C. (260° F.) in the C₅ range; i.e., about 35° C.(95° F.), and an end point (EP) at a temperature greater than or equalto about 127° C. (260° F.). The boiling points for these fractions aredetermined using the procedure known as ASTM D86-82. A heavy naphthafraction suitable as the only feed or a secondary feed to the riser mayhave an IBP at or above about 127° C. (260° F.) and an EP at atemperature above about 200° C. (392° F.), preferably between about 204°and about 221° C. (400° and 430° F.). A full range naphtha fractionsuitable as the only feed or a secondary feed to the riser may have aninitial boiling point (IBP) below about 127° C. (260° F.) in the C₅range; i.e., about 35° C. (95° F.) and an EP at a temperature aboveabout 200° C. (392° F.), preferably between about 204° and about 221° C.(400° and 430° F.).

The reactor vessel 20 is in downstream communication with the riser 10.In the reactor vessel, the carbonized catalyst and the gaseous productare separated. The resulting mixture of gaseous product hydrocarbons andcarbonized catalyst continues upwardly through the riser 10 into thereactor vessel 20 in which the carbonized catalyst and gaseous productare separated. A pair of disengaging arms 22 may tangentially andhorizontally discharge the mixture of gas and catalyst from a top of theriser 10 through one or more outlet ports 24 (only one is shown) into adisengaging vessel 26 to effect partial separation of gases from thecatalyst. Two, three or four disengaging arms 22 may be used dependingon the size of the FCC unit.

A transport conduit 28 carries the hydrocarbon vapors, includingstripped hydrocarbons, stripping media and entrained catalyst to one ormore cyclones 30 in the reactor vessel 20 which separates carbonizedcatalyst from the product hydrocarbon gaseous stream. The disengagingvessel 26 is partially disposed in the reactor vessel 20 and can beconsidered part of the reactor vessel 20. A collection plenum 34 in thereactor vessel 20 gathers the separated hydrocarbon gaseous streams fromthe cyclones 30 for passage to an outlet nozzle 36 and eventually into afractionation recovery zone (not shown). Diplegs 38 discharge catalystfrom the cyclones 30 into a lower bed 29 in the reactor vessel 20. Thecatalyst with adsorbed or entrained hydrocarbons may eventually passfrom the lower bed 29 into an optional stripping section 40 across ports42 defined in a wall of the disengaging vessel 26. Catalyst separated inthe disengaging vessel 26 may pass directly into the optional strippingsection 40 via a bed 41. A fluidizing conduit 45 delivers inertfluidizing gas, typically steam, to the stripping section 40 through afluidizing distributor 46. The stripping section 40 contains baffles 43,44 or other equipment to promote contacting between a stripping gas andthe catalyst. The stripped, carbonized catalyst leaves the strippingsection 40 of the disengaging vessel 26 of the reactor vessel 20 with alower concentration of entrained or adsorbed hydrocarbons than it hadwhen it entered or if it had not been subjected to stripping. Thecarbonized catalyst may leave the disengaging vessel 26 of the reactorvessel 20 through a spent catalyst conduit 48 and feed into theregenerator vessel 50 at a rate regulated by a control valve 51. Anoptional second portion of the carbonized catalyst that has been cokedin the reactor riser 10 may leave the disengaging vessel 26 of thereactor vessel 20 and be fed back to the riser 10, but this embodimentis not shown.

The riser 10 of the FCC process is maintained at high temperatureconditions which generally include a temperature above about 425° C.(797° F.). In an embodiment, the reaction zone is maintained at crackingconditions which include a temperature of from about 480° to about 621°C. (896° to 1150° F.) at the riser outlet port 24 and a pressure fromabout 69 to about 517 kPa (gauge) (10 to 75 psig) but typically lessthan about 275 kPa (gauge) (40 psig). The catalyst-to-oil ratio, basedon the weight of catalyst and feed hydrocarbons entering the bottom ofthe riser, may range up to 30:1 but is typically between about 4:1 andabout 10:1 and may range between 7:1 and 25:1. Hydrogen is not normallyadded to the riser, although hydrogen addition is known in the art.Steam may be passed into the riser 10 and reactor vessel 20 equivalentto about 2-35 wt-% of feed. Typically, however, the steam rate will bebetween about 2 and about 7 wt-% for maximum gasoline production andabout 10 to about 20 wt-% for maximum light olefin production. Theaverage residence time of catalyst in the riser may be less than about 5seconds. The type of catalyst employed in the process may be chosen froma variety of commercially available catalysts. A catalyst comprising azeolitic material such as Y zeolite is preferred, but the older styleamorphous catalysts can be used if desired. Additionally,shape-selective additives such as ZSM-5 may be included in the catalystcomposition to increase light olefin production.

The regenerator vessel 50 is in downstream communication with thereactor vessel 20. In the regenerator vessel 50, coke is combusted fromthe portion of carbonized catalyst delivered to the regenerator vessel50 by contact with an oxygen-containing gas such as air to provideregenerated catalyst. The regenerator vessel 50 may be a combustor typeof regenerator for completely regenerating carbonized catalyst. However,other regenerator vessels and other flow conditions may be suitable forthe present invention. The spent catalyst conduit 48 feeds carbonizedcatalyst to a lower chamber 52. The carbonized catalyst from the reactorvessel 20 usually contains carbon in an amount of from 0.2 to 2 wt-%,which is present in the form of coke. An oxygen-containing combustiongas, typically air, enters the lower chamber 52 of the regeneratorvessel 50 and is distributed by a distributor 54. As the combustion gasenters the lower chamber 52, it contacts carbonized catalyst enteringfrom spent catalyst conduit 48 and lifts the catalyst 52. The oxygen inthe combustion gas contacts the carbonized catalyst and combustscarbonaceous deposits from the catalyst to at least partially regeneratethe catalyst and generate flue gas.

In an embodiment, to accelerate combustion of the coke in the lowerchamber 52, hot regenerated catalyst from a dense catalyst bed 59 in anupper chamber 56 may be recirculated into the lower chamber 52 via anexternal recycle catalyst conduit 58. Mixing hot catalyst from the densecatalyst bed 59 with relatively cooler carbonized catalyst from thespent catalyst conduit 48 entering the lower chamber 52 raises theoverall temperature of the catalyst and gas mixture in the lower chamber52. The mixture of catalyst and combustion gas in the lower chamber 52ascends through a frustoconical transition section to the transport,riser section 60 of the lower chamber 52.

The regenerator vessel 50 also includes an upper chamber 56. The mixtureof catalyst particles and flue gas is discharged from an upper portionof the riser section 60 into the upper chamber 56. Substantiallycompletely regenerated catalyst may exit the top of the transport, risersection 60, but arrangements in which partially regenerated catalystexits from the lower chamber 52 are also contemplated. Discharge iseffected through a disengaging device 62 that separates a majority ofthe regenerated catalyst from the flue gas. Cyclones 64 further separatecatalyst from ascending gas and deposits catalyst through dip legs intodense catalyst bed 59. Flue gas exits the cyclones 64 and collects in aplenum 66 for passage to an outlet nozzle 69 of regenerator vessel 50and perhaps into a flue gas or power recovery system (not shown). Afluidizing conduit delivers fluidizing gas, typically air, to the densecatalyst bed 59 through a fluidizing distributor 68, so the catalystwill fluidly exit through the catalyst conduits 58 and 12.

The regenerator vessel 50 typically has a temperature of about 594 toabout 732° C. (1100 to 1350° F.) in the lower chamber 52 and about 649to about 760° C. (1200 to 1400° F.) in the upper chamber 56. Theregenerated catalyst conduit 12 is in downstream communication with theregenerator vessel 50 and communicates with the riser 10. Regeneratedcatalyst from dense catalyst bed 59 is transported through regeneratedcatalyst conduit 12 from the regenerator vessel 50 back to the reactorriser 10 through the control valve 14 and catalyst inlet 15 where itagain contacts feed as the FCC process continues.

The riser 10 may comprise a lower chamber 11 and an upper reaction zone17 in the riser. The portion of the riser defining the upper reactionzone 17 may be made of chrome steel. The lower chamber 11 may include ahemispherical bottom. The catalyst and feed distributor 4may be providedat the interface between the lower chamber 11 and the upper reactionzone. In an embodiment, the regenerated catalyst conduit 12 may connectto the lower chamber 11 at a wall 70 of the lower section at the inlet15. A fluidizing gas distributor 19 may be located in the lower chamber11 to emit fluidization medium such as steam to urge catalyst upwardlythrough the lower chamber 11 at a relatively high density. In thisembodiment, the lower chamber 11 is in downstream communication with thecatalyst inlet 15 and the fluidizing gas distributor 19.

An intermediate plenum 13 is provided between lower chamber 11 and thereaction zone 17. In an embodiment, one or a plurality of feed inlets 18to the plenum 13 may provide hydrocarbon feed to the plenum which is indownstream communication with the feed inlet 18. If the hydrocarbon feedis vaporous before injection, a single feed inlet may be sufficient. Ifthe hydrocarbon feed is liquid before injection, a plurality of feedinlets 18 may be necessary. The feed inlets 18 may comprise feeddistributors that inject hydrocarbon feed along with an atomizing fluidsuch as steam in a manner that makes the hydrocarbon feed readilysusceptible to vaporization. The atomizing fluid assists in thegeneration of small droplets of hydrocarbon feed upon injection, so thatthe liquid feed can readily vaporize upon injection. Also, the smalldroplet size allows for easier distribution of feed across the crosssection of the riser.

FIG. 2 is a partial elevational view of FIG. 1 showing the catalyst andfeed distributor 4. The lower chamber 11 has a barrier 72 at its upperend. The barrier 72 and a plate 74 define the intermediate plenum 13with the wall of the riser 70. The plate 74 also defines a lower end ofthe reaction zone 17. The plate 74 has a first opening 76 and a secondopening 78. The plate 74 may be flat or curved but in an aspect may notinclude a corner that defines an acute angle except perhaps along themargins of the plate. In an embodiment, the first opening 76 in theplate 74 is for passing hydrocarbon feed from the plenum 13 into thereaction zone 17. Consequently, the plenum 13 is in downstreamcommunication with the feed inlet 18. The plenum 13 communicates withthe reaction zone 17 through the first opening 76, so the reaction zone17 is in downstream communication with the plenum. The first opening 76is in downstream communication with the plenum 13.

In a further aspect, the plate 74 may be equipped with a nozzle 80 toprovide the opening 76 for passing hydrocarbon feed to the reaction zone17. In an aspect, the plate 74 has a multiplicity of first openings 76which include the first opening 76. In a still further aspect, the plate74 may be a perforated plate with a multiplicity of first openings 76for passing hydrocarbon feed from the plenum 13 into the reaction zone17. In an even further aspect, the plate 74 may be equipped with amultiplicity of nozzles 80 that provide a multiplicity of first openings76 for passing hydrocarbon feed from the plenum 13 into the reactionzone 17. A first opening 76 can be provided in the nozzle 80 which is indownstream communication with the plenum 13 if the plate is equippedwith a nozzle 80.

In a further embodiment, shown in FIG. 3, is a further enlarged, partialelevational view of section A of FIG. 2. The plate 74 may be equippedwith a nozzle 80 in an aperture 81 to provide the first opening 76 inthe plate 74. In an aspect, the plate 74 may be equipped with amultiplicity of nozzles 80 in a multiplicity of respective apertures 81in the plate to provide the multiplicity of first openings 76 in theplate 74. The nozzles may have two different inner diameters atrespective ends. A dual-diameter nozzle 80 provides a means toindependently set the jet outlet velocity into the reaction zone 17 andthe pressure drop across the plate 74 to properly distribute vaporoushydrocarbon feed across the cross-section of the riser 10. The jetoutlet velocity of the feed is adjusted by the area of the outletopening 82 in the nozzle 80 located in the reaction zone 17 while thepressure drop is set by the area of the inlet opening 84 in the nozzle80 located in the plenum 13. The multiplicity of first openings 76 arein downstream communication with the plenum 13 in an aspect through thenozzle or nozzles 80.

Turning back to FIG. 2, in this embodiment, the second opening 78 in theplate 74 is for passing catalyst from the lower chamber 11 to thereaction zone 17. The second opening 78 is in downstream communicationwith the lower chamber 11. The plate 74 is equipped with a tube 86 toprovide the second opening 78 for communicating the lower chamber 11with the reaction zone 17 through the second opening 78. In an aspect,the tube 86 extends from the barrier 72 to provide an opening 88 in thebarrier 72 to the plate 74 to provide the second opening 78 in theplate. In a further aspect, the tube 86 extends through the barrier 72to provide the opening 88 in the barrier and through the plate 74 toprovide the second opening 78 in the plate. A second opening 78 can beconsidered provided in the tube 86 which may be in downstreamcommunication with the lower chamber 11. The second opening 78 may be indownstream communication with the lower chamber 11 via the tube 86. Itis sufficient, that the tube 86 communicate the lower chamber 11 withthe reaction zone 17 without communicating with the plenum 13.Consequently, the reaction zone 17 is in downstream communication withthe lower chamber 11 through the second opening 78, tube 86 and theopening 88, but the plenum 13 is not in communication with the lowerchamber 11 through the tube 86.

FIG. 3 also shows the tube 86 extending between the opening 88 in thebarrier 72 and the second opening 78 in the plate 74. The tube 86extends through the plenum 13 to provide communication between thereaction zone 17 and the lower chamber 11.

The tube 86 has a first end 90 that may extend from or through anaperture 91 in the barrier 72 to provide the opening 88 in the barrier.The tube 86 extends through the plenum 13. The tube 86 has a second end92 that may extend to or through the aperture 93 in the plate 74 toprovide the second opening 78 in the plate 74 to provide communicationbetween the reaction zone 17 and the lower chamber 11.

In an aspect, the barrier 72 may have a plurality of openings 88 whichincludes the opening 88 for passing catalyst from the lower chamber 11into the reaction zone 17. In a further aspect, the barrier may beequipped with a plurality of tubes 86 in a plurality of respectiveapertures 91 that provide the plurality of openings 88 proximate thefirst end 90 for passing hydrocarbon feed from the lower chamber 11 intothe reaction zone 17. In a further aspect, the plate 74 may have aplurality of second openings 78 which include the second opening 78 forpassing catalyst from the lower chamber 11 to the reaction zone 17. Inthis aspect, the plate 74 may be equipped with the plurality of tubes 86in a plurality of respective apertures 93 that provide the plurality ofsecond openings 78 proximate the second end 92 for passing hydrocarbonfeed from the lower chamber 11 into the reaction zone 17.

In this aspect, a plurality of tubes 86 may communicate the lowerchamber 11 with the reaction zone 17. Consequently, the plurality oftubes 86 may have first ends 90 that extend from or through the barrier72 to provide the plurality of openings 88 in the barrier. The tubes 86extend through the plenum 13 and to or through the plate 74 at theirsecond ends 92 to provide the plurality of second openings 78 in theplate 74. The plurality of second openings 78 are in downstreamcommunication with the lower chamber 11 in an aspect through therespective tubes 86.

FIG. 4 is a sectional view taken from segment 4-4 of FIG. 2. Themultiplicity of first openings 76 and the plurality of second openings78 are spaced uniformly over the cross section of the plate 74. In thisembodiment, the uniformly spaced first openings 76 and second openings78 are spaced uniformly over the cross section of the riser 10 todistribute hydrocarbon feed and catalyst evenly over the cross sectionof the riser. The distributor 4 distributes catalyst and hydrocarbonfeed evenly together over the cross section of the riser to provide moreintimate contact in the riser 10 as they flow concurrently from the samelocation.

With respect to all of the FIGS., in a first embodiment, a process forfluid catalytic cracking using the catalyst and feed distributor 4comprises feeding hydrocarbon feed to the plenum 13 through a feed inlet18 which may be a feed distributor especially when the feed is in liquidphase prior to injection into the plenum. The hydrocarbon may vaporizein the plenum 13 if it is not already in vapor phase. Hydrocarbon feedis passed from the plenum 13 into the reaction zone 17 through a firstopening 76 in the plate 74. Hydrocarbon feed may pass from the plenum 13into the reaction zone 17 through a first opening or a multiplicity offirst openings 76 in the plate 74 which distribute the hydrocarbon feeduniformly over a cross section of the reaction zone 17 of the riser 10.The hydrocarbon feed may pass through a nozzle 80 providing the firstopening 76 or a multiplicity of nozzles 80 providing the first openings76 or the multiplicity of first openings 76 in the plate 74 into thereaction zone 10, respectively.

In this embodiment, catalyst is fed to the lower chamber 11 of the riser10 from the regenerated catalyst conduit 12 through catalyst inlet 15.The catalyst is propelled upwardly in the lower chamber 11 by fluidizinggas from fluidizing gas distributor 19 in the riser 10. The barrier 72limits upward movement of the catalyst except through opening 88 oropenings 88 in the barrier. Catalyst exits from the lower chamber 11through an opening 88, or in an aspect through a tube 86 providing theopening 88. Catalyst may travel upwardly from a lower end 90 of the tube86, through the plenum 13, through second opening 78 in the plate 74, toan upper end 92 of the tube 86 from which it passes into the reactionzone 17. The catalyst passes through the plate 74 as it exits the plenum13. In an aspect, the catalyst exits the lower chamber 11 through aplurality of openings 88, passes through the plenum 13 and through theplurality of second openings 78 in the plate 74 and into the reactionzone 17 through the plurality of tubes 86. The plurality of tubes 86 arearrayed uniformly over the cross section of the riser 10 to distributethe catalyst uniformly over a cross section of the reaction zone 17 ofthe riser. While the catalyst passes through the plenum 13, the tubes 86isolate the catalyst from the hydrocarbon feed until they both enter thereaction zone 17. The catalyst and the hydrocarbon feed both passupwardly through the plate 74 into the reaction zone 17. The hydrocarbonfeed then contacts with the catalyst in a reaction zone 17 of the riser10 in a manner well distributed over the cross section of the riser 10.

In an additional embodiment, it is contemplated that in the catalyst andfeed distributor 4, catalyst may be passed to the plenum 13 anddistributed through a first opening 76 or a multiplicity of firstopenings 76 into the reaction zone 17 and hydrocarbon feed may be fed tothe lower chamber 11 and passed through a tube 86 or tubes 86 through asecond opening 78 or a plurality of second openings 78 into the reactionzone 17 to be contacted with catalyst therein. The catalyst would beisolated from the feed as the feed passes through the plenum 13.Revisions such as sizing would have to be made to the embodiments in theFIGS. and the plenum 13 would have to be in downstream communicationwith the catalyst inlet 15 and the lower chamber 11 would have to be indownstream communication with the feed inlet 18. Other changes would beapparent from the teachings herein.

The FIGS. depict the invention without showing refractory. However, itis anticipated that one and/or both sides of the barrier 72, the plate74, all nozzles 80, all tubes 86, and the interior of the riser would becoated with a layer of refractory that is not shown.

Preferred embodiments of this invention are described herein, includingthe best mode known to the inventors for carrying out the invention. Itshould be understood that the illustrated embodiments are exemplaryonly, and should not be taken as limiting the scope of the invention.

Without further elaboration, it is believed that one skilled in the artcan, using the preceding description, utilize the present invention toits fullest extent. The preceding preferred specific embodiments are,therefore, to be construed as merely illustrative, and not limitative ofthe remainder of the disclosure in any way whatsoever.

In the foregoing, all temperatures are set forth in degrees Celsius and,all parts and percentages are by weight, unless otherwise indicated.Pressures are given at the vessel outlet and particularly at the vaporoutlet in vessels with multiple outlets.

From the foregoing description, one skilled in the art can easilyascertain the essential characteristics of this invention and, withoutdeparting from the spirit and scope thereof, can make various changesand modifications of the invention to adapt it to various usages andconditions.

The invention claimed is:
 1. A process for fluid catalytic crackingcomprising: passing catalyst to a reaction zone of a riser through aplurality of tubes which distribute said catalyst uniformly over a crosssection of said reaction zone of said riser through a plate; feedinghydrocarbon feed to the reaction of a riser through said plate; andcontacting the feed with the catalyst in a reaction zone of the riser.said catalyst exits from said chamber through a tube.
 2. The process ofclaim 1 further comprising passing said catalyst and feeding saidhydrocarbon feed upwardly through said plate.
 3. The process of claim 1further comprising: feeding catalyst to a riser; propelling the catalystupwardly in the riser; feeding hydrocarbon feed to a plenum; passing thecatalyst through said plenum while isolating the catalyst from the feed;and passing said hydrocarbon feed from said plenum into said reactionzone.
 4. The process of claim 1 further comprising passing saidhydrocarbon feed through first openings in said plate from a plenum intosaid reaction zone.
 5. The process of claim 1 wherein said catalyst isfed to a chamber of said riser.
 6. The process of claim 5 wherein saidcatalyst exits from said chamber through said plurality of tubes.
 7. Theprocess of claim 6 wherein said catalyst passes through said pluralityof tubes through a plenum and into said reaction zone.
 8. The process ofclaim 7 wherein said catalyst passes through said plate as it exits saidplenum.
 9. The process of claim 8 wherein said catalyst exits saidchamber, passes through said plenum and into said reaction zone throughsaid plurality of tubes which distribute said catalyst uniformly over across section of said reaction zone of said riser.
 10. The process ofclaim 9 wherein said hydrocarbon feed passes into said reaction zonethrough a perforated plate comprising a multiplicity of first openingswhich distribute said hydrocarbon feed uniformly over a cross section ofsaid reaction zone of said riser.
 11. A process for fluid catalyticcracking comprising: passing hydrocarbon feed upwardly in a riser from amultiplicity of first openings spread out uniformly over a cross sectionof said riser; passing catalyst upwardly in the riser from a pluralityof second openings spread out uniformly over a cross section of saidriser; and contacting said catalyst and said hydrocarbon feed in saidriser.
 12. The process of claim 11 further comprising passing saidcatalyst and said hydrocarbon feed through a plate.
 13. The process ofclaim 11 further comprising: feeding said hydrocarbon feed to a plenum;passing the catalyst through said plenum while isolating the catalystfrom the feed; and contacting the feed with the catalyst in a reactionzone of the riser.
 14. The process of claim 13 further comprisingpassing said catalyst through a plurality of tubes through said plenumand out of said plurality of openings into said reaction zone.
 15. Theprocess of claim 14 wherein said catalyst is fed to a chamber of saidriser and said catalyst exits from said chamber through said pluralityof tubes.
 16. The process of claim 13 further comprising passing saidhydrocarbon feed through a multiplicity of openings in a plate from saidplenum into said reaction zone.
 17. A process for fluid catalyticcracking comprising: feeding catalyst to a chamber of a riser; saidcatalyst exiting said chamber, passing through a plenum and into areaction zone through a plurality of tubes which distribute saidcatalyst uniformly over a cross section of said reaction zone of saidriser; feeding hydrocarbon feed to said plenum, said hydrocarbon feedpassing from said plenum into said reaction zone through a platecomprising a multiplicity of openings which distribute said hydrocarbonfeed uniformly over a cross section of said reaction zone of said riser;and contacting the feed with the catalyst in a reaction zone of theriser.
 18. The process of claim 17 further comprising propellingcatalyst upwardly in said chamber with a fluidizing gas.
 19. The processof claim 17 further comprising passing said catalyst and saidhydrocarbon feed through said plate.